The language/Localization Pack for the public test 7.0 is still currently being completed.
Please be patient will I try to get this released as soon as is possible.

In the mean time if waiting is not a option and you are a little technical minded, you may wish to try the following.
Using a file manager, such as windows explorer.
Goto your 6.7 retail world of tanks directory, and into the directory similar to the following (or where ever you have the 6.7 retail world of tanks installed)
c:\games\World_of_Tanks\res\text\LC_MESSAGES
Select all, except

ingame_gui.mo

dialogs.mo

Poniżej oryginalny folder LC_Messages z RU.

After selecting all the files except the above two mentioned files, right click, select copy.

Then goto the similar directory where you install the 7.0 public test IE:
c:\games\World_of_Tanks70publictest\res\text\LC_MESSAGES

And paste, Selecting override existing files.

This will transfer "most" of the client to English.
Without creating errors with "sell tanks" "Cap meter" "End of game stats" like copying all localization files will..

*Please note the above is a player made solution, (Thanks RelicShadow) for those not wishing to wait for the real language pack to be released.
It may cause unexpected unforeseen errors, and may require you to re-install when the official language pack is released. So it is preferable to wait for the official language packs. However : ) Some people prefer not to wait. So.. This will help as a a temporary fix.